Multi-pressure hydraulic supply system for an automatic transmission

ABSTRACT

A pressurized fluid supply system for a vehicle transmission is provided. The fluid supply system has a pump with at least high and low pressure outputs that supplies high and low pressure components via a directional valve. The pressurized fluid supply system minimizes the parasitic loss upon a vehicle engine.

FIELD OF THE INVENTION

The present invention relates to pressurized hydraulic fluid supplysystem for automatic transmissions.

BACKGROUND OF THE INVENTION

Automatic transmissions for vehicles require a source of pressurizedfluid. The source of pressurized fluid is typically a hydraulic pumppowered by the vehicle engine. The pump is parasitic load on the vehicleengine. In a quest to improve vehicle mileage, it is desirable tominimize the parasitic load provided by the hydraulic pump of thetransmission.

SUMMARY OF THE INVENTION

To make manifest the above noted and other desires, a revelation of thepresent invention is brought forth. In a preferred embodiment, thepresent invention provides freedom of a hydraulic system for anautomatic transmission having a pump with both low and high pressureoutlets. One of the pressure outlets is connected with a directionalvalve having a first position delivering pressurized fluid from anoutlet range matched pressurized fluid consuming components, a secondposition delivering pressurized fluid to non-range matched pressurizedfluid components, and a third position delivering non-pressurized fluidto an inlet of the pump.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is schematic view of a pressurized fluid system for an automotivevehicle transmission according to the present invention;

FIG. 2 is a schematic view of an alternate embodiment pressurized fluidsupply system to that shown in FIG. 1;

FIG. 3 is a schematic view of a pump utilized in the pressurized fluidsystem of the present invention; and

FIG. 4 is a schematic view of yet another embodiment of a pump utilizedas a pressurized fluid source for a pressurized fluid system accordingto the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

Referring to FIG. 1, a multiple pressure hydraulic supply system for anautomotive transmission is provided. The system 7 has a pressurizedfluid source provided by a balanced vane pump 10. Pump 10 has a highpressure outlet 12 and a low pressure outlet 14. The inlet 16 of thepump 10 is connected with a sump 18 via a filter 20. Inlet 16 isconnected with a lower branch 22 and an upper branch 24 of the pump 10.

Outlet 12 is connected with a line 26. The high pressure line 26connects the high pressure outlet 12 with high pressure hydraulic fluidconsuming components 30 which are various clutches, and gear actuatorsof the transmission.

Pump low pressure outlet 14 and filter 34 is connected with adirectional valve 36, which is shown as a direct control, electricallyactuated valve. Alternatively this can be a two-stage directional valveas well. The directional valve 36 has a first position 35 connecting thedirectional valve via a line 41 with low pressure consuming functioncomponents 40 which includes cooling and lubrication for the clutch,gears, and bearings. In a third position 37 directional valve 36connects the low pressure outlet with the pump inlet line 16 via line42. In a second position directional valve 36 is connected the outlet 14with lines 44 and 26 which connects with high pressure components 30.The high pressure line 26 is also connected with a pressure regulatorvalve 48.

The pressure regulator valve 48 is used to properly control the linepressure in high pressure line 26, and bleed the surplus flow to lowpressure lube/cooling 40 as well as dump the excessive flow back to theinlet 16 of the pump 10. The pressure regulator valve 48 has one endunder the feedback pressure while the other ends with a bias spring 63and a pilot pressure 65, which connects with a proportional pressurecontrol solenoid valve (not shown). The pressure regulator valve 48includes two supply ports 67 connecting with the high pressure line 26.A port 69 connects with a low pressure cooler/lube line 53 and a port 71connects with the pump inlet 16.

In FIG. 1, the pressure regulator valve 48 is shown in the closed,non-regulating position 52, at such position the engine either is off orrunning at idle speeds when there is no excess flow. When the hydraulicpressure supplied from the pump 10 increases and the flow is excessive,the pressure regulator valve 48 moves to a second regulating position56, where part of the flow is bled off to the low pressure cooler/lubeline 53. When the engine speed further increases to mid or highoperating speed, the pressure regulator valve 48 is moved to a thirdposition 54. At this point, the valve flow bleeds both to the lowpressure lube/cooling line 40 and to the pump inlet 16 line. Under allabove three operating conditions, the regulated high pressure fluid isprovided to the high pressure actuation such as gear shifting or clutchactuation indicated as 30 in FIG. 1

In operation when the engine speed is low, but there is a need tomaintain the adequate line pressure, the directional valve 36 switchesto position 36 and main pressure regulator will be at any intermediateposition between 52 and 56 depending on the line pressure requirement.Under such condition, flow from both sides of the pump will go to mainline 26.

When the engine speed is above certain point, the vehicle is at cruisespeed but neither requires the high line pressure for actuation or thehigh cooling/lubrication flow for clutches and gears, the high pressureside of the pump will be capable to provide enough flow through line 10to maintain the adequate line pressure. Under such condition, thedirectional valve 36 will move to the middle position 37, the flow fromthe low pressure side of the pump 14 re-circulates back to the pumpinlet 16, which consumes the minimum power. The main regulator 48 atthis moment, depending on the required line pressure, can be at anyintermediate position.

When the vehicle is at high energy launch, it requires both the moderatehigh line pressure for actuation and high cooling/lubrication flow.Under such condition, because of the reasonably high engine speed, theflow from the high pressure side of the pump is capable to maintainadequate line pressure through line 10 and 26. The main pressureregulator is at any intermediate position of 52, 56, or 54 depending onthe required line pressure. The directional valve 36 will be switched toposition 35, which routes the flow from low pressure side of the pump toline 41, and connects directly to the clutch and gear lube line.

Referring to FIG. 2 an alternate preferred embodiment hydraulic supplysystem of the present invention is provided with items performingfunctions identical or similar to that of FIG. 1, being given identicalreference numbers. Vane pump 10 has a high pressure outlet 12 connectedwith a directional valve 72 via a filter 70 and provided in a highpressure line 26. In a first position 74 the directional-valve 72connects the high pressure outlet 12 with an accumulator 86, whichconnects with the high pressure hydraulically powered components 30which include gear actuation, and clutch actuation of the transmission.When directional valve 72 is moved from its first position 74 connectingwith the accumulator and high pressure components 30, to a thirdposition 76, fluid from outlet 12 recirculates into the inlet 16 of thepump 10. When directional valve 72 is moved to its second position 78the outlet 12 is fluidly connected with low pressure line 88 to bedelivered to cooling/lube line of bearing or gear 90, and clutch 92 viaa flow control valve 91.

In operation high pressure outlet 12 charges accumulator 86 when thedirectional valve is in position 74. Once the accumulator 86 is fullycharged, solenoid valve 72 is switched to position 76 or 72 dependingupon operating needs. If a high actuation load is needed for highpressure components 30, especially when engine speed is low, thencomponents 30 can receive pressurized fluid from both the high pressureoutlet 12 and the accumulator 86, or both if needed. When there is nohigh flow needed for actuation of the components 30, directional valve72 can proceed to position 76. In such operating mode, thecooling/lubrication flow requirements can be met fully by low pressureoutput portion 14 while the output portion 12 recirculates back to pumpinlet. When high lube flow is required and no longer met by the pumpoutput 14 alone during high energy launching, directional valve 72 willbe switched to position 78 and flow from the outlet 12 and outlet 14will both go to the cooling/lube circuit.

FIG. 3 illustrates a binary gear pump 100 having a high pressure output12, a low pressure output 14, suction inlets 119 and 121. Pump 110 canbe a substitute for vane pump 10 shown in FIGS. 1 and 2. In anotheralternative pump arrangement 210 is provided having a high pressure pump211 driven by the engine 207 via pulley, direct shaft or via a shaftpowered by the transmission which in turn powers the low pressure outletpump 215 via a clutch 213. When low pressure output is undesirableclutch 213 will open disconnecting low pressure pump 215.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A multiple pressure hydraulic supply system for an automotive vehicle transmission, said transmission having at least a first lower pressure range of pressurized fluid consuming components and a second higher pressure range of pressurized fluid consuming components, said pressure hydraulic supply system comprising: a pressurized fluid source having a first low pressure output and a second high pressure output; a directional valve connected with one of said first and second pressure outputs, said directional valve having a first position delivering said one of said first and second pressure outputs with corresponding pressure range matching first or second components, said directional valve having a second position delivering said one of said first and second pressure outputs with a non-matching pressure range first or second components, said directional valve having a third position to re-circulate fluid to an inlet of said pressurized fluid source.
 2. The hydraulic supply system as provided in claim 1 wherein said directional valve is connected with said low pressure outlet.
 3. A hydraulic supply system as provided in claim 1 wherein said directional valve is connected with said high pressure outlet.
 4. A multiple pressure hydraulic supply system for an automotive vehicle transmission comprising: a pump having a high pressure output and a low pressure output; and a directional valve connected with said high pressure output, said directional valve having a first position delivering high pressure fluid to a high pressure component, a second position to deliver fluid to a low pressure component, and a third position to re-circulate fluid to a pump inlet.
 5. A hydraulic supply system as provided in claim 4 further including an accumulator connected with said first directional valve and said high pressure component.
 6. A hydraulic supply system as provided in claim 4 having a check valve between said directional valve and said high pressure component.
 7. A hydraulic supply system as described in claim 2 further including a check valve between said low pressure outlet and said low pressure directional valve.
 8. A hydraulic supply system as described in claim 1 wherein said pressurized fluid source is a balanced vane pump.
 9. A hydraulic supply system as described in claim 1 wherein said pressurized fluid system is a dual pressure output gear pump.
 10. A hydraulic supply system as described in claim 1 wherein said pressurized fluid source is high pressure pump and a low pressure pump with a clutch connection with said high pressure pump.
 11. A multiple pressure hydraulic supply system for an automotive transmission comprising: a pump having a high pressure output and a low pressure output; a directional valve connected with said high pressure output, said directional valve having a first position delivering high pressure fluid to a high pressure consuming component, a second position to deliver fluid to a low pressure consuming component, and a third position to re-circulate fluid to an inlet of said pump; and an accumulator connected with said high pressure component.
 12. A multiple pressure hydraulic supply system as described in claim 1, wherein said directional valve is connected with said low pressure output and said high pressure output is connected with a fluid pressure regulator valve having at least one position connecting said high pressure outlet with said low pressure consuming component and a second position connecting said high pressure outlet with said low pressure consuming component and an inlet of said pressurized fluid source and said regulating valve further having a third position preventing fluid communication between said high pressure outlet and said low pressure consuming component and said inlet of said pressurized fluid source. 